vn3.1

LFRic Core vn3.1 release notes

Key Changes

• New api for namelist configuration access #175, the old method of access is deprecated. Usage is detailed in the Using the config object
• Changes to the partitioning strategy so that MPI ranks for cubed-sphere runs are no longer limited to a factor of 6, and can now run with a factor of 2 or 3. #220

Breaking Changes

These changes will affect suites upgrading to this release

• No known breaking changes at this release.

Known Issues

• No known issues at this release.

Linked Changes

This release is part of the 2026.03.1 Simulation Systems Release..

What's Changed

• Sphinx setup initial setup by Andrew Coughtrie (@andrewcoughtrie) in #1
• Some initial documentation. by Andrew Coughtrie (@andrewcoughtrie) in #2
• First draft of DistMem doc. by Mike Hobson (@mike-hobson) in #4
• Configurator documentation by Matthew Hambley (@MatthewHambley) in #10
• Import top-level LFRic documentation by Steve Mullerworth (@stevemullerworth) in #9
• Improve data model document by Steve Mullerworth (@stevemullerworth) in #15
• Addressing the most obvious flaws in the dist mem docs. by Mike Hobson (@mike-hobson) in #11
• Added XIOS file definition standards as well as some general tweaks. by Andrew Coughtrie (@andrewcoughtrie) in #17
• First draft of clock and time documentation. by Matthew Hambley (@MatthewHambley) in #19
• Add deploy docs badge by Andrew Coughtrie (@andrewcoughtrie) in #21
• Rename readme and doc deployment by Andrew Coughtrie (@andrewcoughtrie) in #22
• Update the workflow to use newer actions by Andrew Coughtrie (@andrewcoughtrie) in #20
• Doc structure by Steve Mullerworth (@stevemullerworth) in #24
• Add a glossary page with some initial definitions as a starting point… by Ricky Wong (@mo-rickywong) in #27
• Pydata restructure by Andrew Coughtrie (@andrewcoughtrie) in #31
• Update sphinx workflow by Andrew Coughtrie (@andrewcoughtrie) in #32
• Add sphinx design to pip install in workflow by Andrew Coughtrie (@andrewcoughtrie) in #33
• Added the glossary as a link in the guide to documentation by Andrew Coughtrie (@andrewcoughtrie) in #34
• Create CODEOWNERS by Andrew Coughtrie (@andrewcoughtrie) in #36
• Fix edit source link in conf.py by Andrew Coughtrie (@andrewcoughtrie) in #38
• Update module info in readme by Andrew Coughtrie (@andrewcoughtrie) in #39
• Fix link to the GitHub repo by Andrew Coughtrie (@andrewcoughtrie) in #40
• Write-up of external fields. by Matthew Hambley (@MatthewHambley) in #25
• Application schematic added to docs by Steve Mullerworth (@stevemullerworth) in #37
• 30 document prognostics and diagnostics system by Steve Mullerworth (@stevemullerworth) in #35
• Document templaterator and templates by Matthew Hambley (@MatthewHambley) in #51
• Added issue templates by Andrew Coughtrie (@andrewcoughtrie) in #42
• Update figures in the lfric datamodel docs by Andrew Coughtrie (@andrewcoughtrie) in #49
• Data structures by Steve Mullerworth (@stevemullerworth) in #45
• Document Modeldb by Mike Hobson (@mike-hobson) in #50
• Improve issue templates by Andrew Coughtrie (@andrewcoughtrie) in #56
• Correct info on mixed-precision field collection iterators. by Mike Hobson (@mike-hobson) in #61
• 18 sphinx style guide by Steve Mullerworth (@stevemullerworth) in #65
• Some small fixes to the issue templates forms by Andrew Coughtrie (@andrewcoughtrie) in #70
• Fix yaml files by Mike Hobson (@mike-hobson) in #71
• Apply style changes to all the docs by Steve Mullerworth (@stevemullerworth) in #74
• Add info on coupling to the documentation by Mike Hobson (@mike-hobson) in #77
• Fix field collection iterator example code by Mike Hobson (@mike-hobson) in #79
• Getting going documentation by Steve Mullerworth (@stevemullerworth) in #78
• Add Fortran style guide by Steve Mullerworth (@stevemullerworth) in #83
• Doxygen usage copied from SRS and updated by Matthew Hambley (@MatthewHambley) in #67
• Moved configurator documentation to developer guide by Matthew Hambley (@MatthewHambley) in #88
• Mesh generation user guide documentation - Quick Start & Restructure by Ricky Wong (@mo-rickywong) in #63
• Fix the reference numbers for figures in the dist-mem docs. by Mike Hobson (@mike-hobson) in #85
• Clean up the data model doc and move it to developer documentation by Steve Mullerworth (@stevemullerworth) in #89
• Adding unit test documentation by Mike Hobson (@mike-hobson) in #80
• Dependerator documentation by Matthew Hambley (@MatthewHambley) in #87
• 62 documentation add configuration documentation by Ricky Wong (@mo-rickywong) in #84
• Update GitHub actions to bring in line with lfric_apps by Andrew Coughtrie (@andrewcoughtrie) in #94
• Update workflow badge by Andrew Coughtrie (@andrewcoughtrie) in #95
• Update function space documentation for split element orders by mo-jdendy in #91
• Updated modeldb documentation by allynt in #101
• Fixed a missing link by Matthew Hambley (@MatthewHambley) in #102
• Placeholder documentation for components. by Matthew Hambley (@MatthewHambley) in #92
• Introduce the simple I/O system. by Matthew Hambley (@MatthewHambley) in #105
• Introduction to logging framework. by Matthew Hambley (@MatthewHambley) in #104
• Describe the use of "big PF." by Matthew Hambley (@MatthewHambley) in #109
• Update fortran_coding_standards.rst by Mike Hobson (@mike-hobson) in #111
• Make prohibition on application specifics in driver component more explicit by Matthew Hambley (@MatthewHambley) in #112
• Add PSyclone Makefile docs by Oakley Brunt (@oakleybrunt) in #110
• Add deploy target to MakeFile by Andrew Coughtrie (@andrewcoughtrie) in #114
• Add integration testing documentation by Matthew Hambley (@MatthewHambley) in #117
• Update software_dependencies.rst by Andrew Coughtrie (@andrewcoughtrie) in #120
• Update the dist mem docs to explain the alternative to inner halos by Mike Hobson (@mike-hobson) in #121
• Refine comments on kind specification by Steve Mullerworth (@stevemullerworth) in #125
• Migrate Python style guide from SRS by Matthew Hambley (@MatthewHambley) in #124
• A primer for code reviewers by Matthew Hambley (@MatthewHambley) in #122
• Started a page of testing tips by Matthew Hambley (@MatthewHambley) in #123
• Character style by Steve Mullerworth (@stevemullerworth) in #118
• Correct Gnu version and fix formatting by Steve Mullerworth (@stevemullerworth) in #126
• Renamed the main sections of the documentation. by Andrew Coughtrie (@andrewcoughtrie) in #127
• Fix copyright format by Andrew Coughtrie (@andrewcoughtrie) in #128
• Update the README.md file by Andrew Coughtrie (@andrewcoughtrie) in #129
• Document use of the lfric mpi module by Mike Hobson (@mike-hobson) in #130
• Add basic PR template by Andrew Coughtrie (@andrewcoughtrie) in #132
• Simplify the data section by referencing other sections by Steve Mullerworth (@stevemullerworth) in #136
• Extend and refactor logging information by Steve Mullerworth (@stevemullerworth) in #137
• Configuration documentation by Steve Mullerworth (@stevemullerworth) in #138
• Add in details of File_prefix which appears to have been omitted by Ricky Wong (@mo-rickywong) in #139
• Adding a FAQs page by Andrew Coughtrie (@andrewcoughtrie) in #141
• Update glossary.rst by Mike Hobson (@mike-hobson) in #143
• Updated workflow packages to be pegged at specific versions. by Andrew Coughtrie (@andrewcoughtrie) in #142
• An illustration of the testing continuum by Matthew Hambley (@MatthewHambley) in #148
• Code style guide for kernels by Andrew Coughtrie (@andrewcoughtrie) in #145
• Removed system integration testing from diagram but discussed it more… by Matthew Hambley (@MatthewHambley) in #149
• Update README.md by Steve Mullerworth (@stevemullerworth) in #146
• Split GitHub workflows by Andrew Coughtrie (@andrewcoughtrie) in #150
• Add accessibility statement by Steve Mullerworth (@stevemullerworth) in #153
• Add escalation of warnings to errors in the build of the Sphinx docs. by Andrew Coughtrie (@andrewcoughtrie) in #155
• Fix formatting to be more pleasant on mobile devices by Andrew Coughtrie (@andrewcoughtrie) in #159
• Add section on Mesh file contents and Ugrid compliance by Ricky Wong (@mo-rickywong) in #144
• Add reference to log_at_level API by Matthew Hambley (@MatthewHambley) in #160
• Remove date from all copyright statements by Steve Mullerworth (@stevemullerworth) in #162
• Update issue templates by Andrew Coughtrie (@andrewcoughtrie) in #164
• Lfric core git test by James Bruten (@james-bruten-mo) in #161
• fix extraction by James Bruten (@james-bruten-mo) in #165
• Modified files to reduce resources requested by LBC rose stem tasks by Ricky Wong (@mo-rickywong) in #166
• add github files by James Bruten (@james-bruten-mo) in #168
• update dependency by James Bruten (@james-bruten-mo) in #169
• Fix climate runs performance issue. by Jenny Hickson (@jennyhickson) in #170
• add cla files by James Bruten (@james-bruten-mo) in #172
• Pre release vn3.0 by Jenny Hickson (@jennyhickson) in #174
• Release vn3.0 by Jenny Hickson (@jennyhickson) in #178
• Stable to Main, vn3.0 by James Bruten (@james-bruten-mo) in #179
• Docs deploy only triggers on upstream by mo-marqh in #180
• Codeowners update by Andrew Coughtrie (@andrewcoughtrie) in #182
• Add some words about the reason for testing by Matthew Hambley (@MatthewHambley) in #185
• Remove contact details from Issue template by Yaswant Pradhan (@yaswant) in #189
• Update root Readme file. by Andrew Coughtrie (@andrewcoughtrie) in #188
• Change TM to R by Andrew Coughtrie (@andrewcoughtrie) in #193
• Update gitignore by James Bruten (@james-bruten-mo) in #194
• Fail gracefully if the configuration namelist doesn't exist by Mike Hobson (@mike-hobson) in #191
• Fixed duplication of directory ownership, should have been a differen… by Andrew Coughtrie (@andrewcoughtrie) in #190
• Add Harry Shepherd to CONTRIBUTORS.md by Harry Shepherd (@harry-shepherd) in #207
• Remove additional leading space from make message calls by Ed Hone (@EdHone) in #210
• Remove references to FCM following Git migration by Steve Mullerworth (@stevemullerworth) in #208
• Reusing xt xmap by Mike Hobson (@mike-hobson) in #198
• add project workflow by James Bruten (@james-bruten-mo) in #214
• Timing Mod wrapper rewrite by Jed Baker (@jedbakerMO) in #201
• Avoid panel_decomposition_mod causing a divide-by-zero by Tom Hill (@tom-j-h) in #227
• Reformat pull request template by Yaswant Pradhan (@yaswant) in #211
• Verniered Calipers performance 25 core by mo-marqh in #233
• Correction to team in code owner file by Thomas Bendall (@tommbendall) in #244
• Mpifort makefile by Andrew Coughtrie (@andrewcoughtrie) in #251
• Small fixes to better enable running with XIOS 3 by Ed Hone (@EdHone) in #218
• Change gitattributes diff to fortran-free-form by Andrew Coughtrie (@andrewcoughtrie) in #253
• Only build docs when docs files changed by Andrew Coughtrie (@andrewcoughtrie) in #256
• Reworked Configuration Namelist Access API by Ricky Wong (@mo-rickywong) in #175
• Add tag to avoid vernier CCE MPI bug by Benjamin Went (@MetBenjaminWent) in #261
• Adding logging to tweak_iodef by Lottie Turner (@mo-lottieturner) in #187
• Update exchange_map_collection with copyright header by Mike Hobson (@mike-hobson) in #228
• Add support for the test suite on monsoon 3 by Sam Clarke-Green (@t00sa) in #248
• Fix jedi config by Ricky Wong (@mo-rickywong) in #264
• Add nonuniform partitioning options to docs by James CS (@jcsmeto) in #267
• Fix Correction to Sampling Physics Winds by Thomas Bendall (@tommbendall) in #221
• Decompose across panels by thomasmelvin in #220
• Add link to milestones to README by Andrew Coughtrie (@andrewcoughtrie) in #268
• update trigger project workflow by James Bruten (@james-bruten-mo) in #269
• Fix averaging kernel used in stochastic physics filter by Thomas Bendall (@tommbendall) in #222
• run remote_init on shared by James Bruten (@james-bruten-mo) in #275
• Allow computation and storage of height at W0 by Thomas Bendall (@tommbendall) in #229
• Take XIOS file frequency configuration from iodef.xml where possible by Ed Hone (@EdHone) in #212
• Add GH_SCALAR_ARRAY to argument_mod by Alistair Pirrie (@mo-alistairp) in #223
• Lift adjustable psyclone command options into adjustable flag by Benjamin Went (@MetBenjaminWent) in #271
• Improve partitioner unit tests by Mike Hobson (@mike-hobson) in #254
• Additions and corrections to code owners files by Thomas Bendall (@tommbendall) in #278
• Allow different meshes to have different maximum halo depths by Thomas Bendall (@tommbendall) in #237
• Catch build system up with name change of generated configuration source by Matthew Hambley (@MatthewHambley) in #281
• Update CODEOWNERS file to have more comprehensive coverage by Andrew Coughtrie (@andrewcoughtrie) in #283
• Remove module scope access of namelist variables by coordinate/native jacobian. by Ricky Wong (@mo-rickywong) in #249
• Apps vn3.1 upgrade by Erica Neininger (@ericaneininger) in #295
• Main to Stable 2026.03.1 by Jenny Hickson (@jennyhickson) in #297

New Contributors

• Andrew Coughtrie (@andrewcoughtrie) made their first contribution in #1
• Mike Hobson (@mike-hobson) made their first contribution in #4
• Matthew Hambley (@MatthewHambley) made their first contribution in #10
• Steve Mullerworth (@stevemullerworth) made their first contribution in #9
• Ricky Wong (@mo-rickywong) made their first contribution in #27
• mo-jdendy made their first contribution in #91
• allynt made their first contribution in #101
• Oakley Brunt (@oakleybrunt) made their first contribution in #110
• James Bruten (@james-bruten-mo) made their first contribution in #161
• mo-marqh made their first contribution in #180
• Yaswant Pradhan (@yaswant) made their first contribution in #189
• Harry Shepherd (@harry-shepherd) made their first contribution in #207
• Ed Hone (@EdHone) made their first contribution in #210
• Jed Baker (@jedbakerMO) made their first contribution in #201
• Tom Hill (@tom-j-h) made their first contribution in #227
• Thomas Bendall (@tommbendall) made their first contribution in #244
• Benjamin Went (@MetBenjaminWent) made their first contribution in #261
• Lottie Turner (@mo-lottieturner) made their first contribution in #187
• Sam Clarke-Green (@t00sa) made their first contribution in #248
• James CS (@jcsmeto) made their first contribution in #267
• thomasmelvin made their first contribution in #220
• Alistair Pirrie (@mo-alistairp) made their first contribution in #223
• Erica Neininger (@ericaneininger) made their first contribution in #295

Full Changelog: https://github.com/MetOffice/lfric_core/commits/vn3.1